An engine-generator set, which may be referred to as a generator or a genset, may include an engine and an alternator or another device for generating electrical energy or power. One or more generators may provide electrical power to a load through a power bus. The power bus, which may be referred to as a generator bus or common bus, transfers the electrical power from the engine-generator set to a load. In many examples, the electrical load on the engine-generator set may vary over time.
The frequency of the output of a synchronous generator is based on the speed of the engine and the number of poles in the generator. In order to provide a constant output frequency, the prime mover may have to operate at a fixed speed. The engine may not need to operate at the fixed speed in order to provide enough power to supply the load, but does so to maintain frequency.
Although allowing the engine speed to decrease at light loads may reduce wear, fuel consumption, and sound emissions from the generator, converting the frequency is required in order to allow the engine speed to decrease from rated speed.